“But we are lucky that he has grown into a sweet little boy. When he’s not in pain or discomfort he is extremely placid and smiley. We just want to make his quality of life better – something every child deserves.”

As a result of his condition, Isaac also has learning difficulties, cerebral visual impairment – which has left him virtually blind, and is unable to eat or speak without support.

Andy and wife Rachel have since pledged to raise funds to help with mobility and well-being as the brave toddler grows up. But unfortunately Isaac was taken ill at the start of the summer holidays, suffering from seizures and breathing problems. He spent the majority of time in hospital from July to September, having a huge impact on Andy’s ability to train for the marathon.

He said: “This made training extremely hard as well as working and juggling caring for and being at the hospital with Isaac and then Rachel and my other kids Connie and Violet.

“There was just no room for intensive training. Unfortunately, I was not allowed to retract his application to rearrange for the following year, but was told I could downgrade to the half marathon instead, so I did just that. I already had some commitment from sponsors and I didn’t want to let anyone down. I tried to train, but only managed around three before the marathon.

“I can’t believe I managed to complete it. It wasn’t ideal not being able to prepare as much as I would have liked, but I am genuinely ecstatic that I managed to make it through.”

Andy’s first chosen charity was School for Parents, which provides a cognitive educational programme to support and help Isaac fulfil his potential. The support has seen Isaac hold his head up independently and have given us and so many local families hope and the strength to try and cope.

The second was Battle Batten, a charity which raises funds for research in honour of Louie and Freddie Dawkins – identical twins who have the degenerative, incurable CLN5 Batten Disease.

Andy’s marathon success comes after wife Rachel took part in the Edinburgh Marathon in May, completing the gruelling 26-mile run in just over six hours.

Andy said: “Rachel set a precedent raising £1,700. If she could do it, then I knew I had better give it my best shot too.”

Andy’s target was to raise a minimum of £500, which has been smashed and currently stands at £650.

He said: “Every penny counts, the pennies all make pounds. We just want to be able to give back and help support those who we have received help from including local charities, hospitals and staff and of course to help fund a brighter future for Isaac and other children like Freddie and Louie.”